Differential-Pressure Relief Valve

A relief valve has been designed to limit the differential pressure between two fluids that are not allowed to be mixed. This valve offers advantages over both simple check valves and simple relief valves. A simple relief valve vents a fluid at the preset absolute relief pressure, but offers no means for limiting the differential pressure between two fluids. A simple check valve can be used to limit the pressure between two fluids, but when the valve opens to relieve differential pressure, one fluid flows into the other one; thus, a simple check valve is not suitable for a system in which the two fluids must not be mixed.